8th Grade Algebra - How to write as polynomial/factoring - Help me on my Test

Alright for my Practice test I have to know how to do these...

It says "Write as a Polynomial"

(5x^2 + 3x - 4) + (3x^2 - 8x - 2) =
a(2-a) =
(a + b + 5)3b =
-4(a - b) =
3x (x^2 + x) =

Please explain to me in simple english how to SOLVE these questions, and show me what to do in different scenarios. I'm the worst student in math in my class but I am trying hard. (I have a learning disability)

And I also Need help on how to Factor polynomials.

Factor

3a^2 - 6a^2b =
4x - 4 =
10x - 5y + 35 =
y^3 - y^2 - y =

and more write as a polynomial


(x-4)^2
(x+3)(x+7)
(x-2)(x+3)
(2a-3)(3a - 4)


PLEASE HELP ME IN TERMS THAT ARE EASY TO UNDERSTAND. Step-by-step would be nice. And explain the different scenarios and such. Thanks.

The test is tomorrow, it has 20 problems, If i study hard today, could i get 100%?

"Write as a polynomial"

(5x^2 + 3x - 4) + (3x^2 - 8x - 2) =
Combine like terms. Like terms are terms that are multiplied by the same variable (to the same degree)
So the like terms are 5x^2 and 3x^2; 3x and -8x; and -4 and -2
5x^2 + 3x^2 = 8x^2
3x - 8x = -5x
-4 - 2 = -6
So all together, that = 8x^2 - 5x - 6

a(2-a) =
Multiply what's out of the parenthesis with what's inside.
So it = 2a - a^2
If you want to write this is a more common form, then it's = -a^2 + 2a

(a + b + 5)3b =
As with the previous one, multiply outside of parenthesis with inside.
3ba + 3b^2 + 15b

-4(a - b) =
Same as before.
-4a + 4b

3x (x^2 + x) =
Same as before.
3x^3 + 3x^2

Factor:
This is basically like above, except you flip it around. You have to take out common terms.

3a^2 - 6a^2b =
What's common between the two terms? Both contain 3a^2.
So now you have 3a^2(something)
To figure out the something, divide each term by 3a^2. You end up with: